The invention involves a device for the optical measurement of an object, in particular for path and/or vibration measurement, using a laser interferometer whose measuring beam is input into the beam path of a microscope, wherein the device has an assembly for approximately parallel shifting of the measuring beam.
Laser interferometers represent ideal measurement structures for high resolution path and/or vibration measurements. The measurements thus take place in a purely optical, i.e., contact-free, manner. They are therefore also particularly suitable for micromechanical, microelectrical or microbiological objects, in which the attachment, for example, of traditional accelerating sensors for other vibration measuring processes, is inherently not possible because of the small mass of the object.
In the measurement of small objects of this type, it is desirable to observe the area to be measured in a microscope and to be able to position the measuring point using the microscope. For this, an assembly is known in which a measuring beam is input over the path of illumination into the beam path of the microscope. Because of the geometrical conditions to be maintained during the input over the illumination path, the interferometer and microscope can only be constructed as a combined unit. The use of this device is thus impeded by the high construction costs, because in addition to the interferometer, a special microscope must also still be manufactured, which, particularly in view of the construction of its illumination path, must be adapted to the interferometer used.
The generic concept of the device described at the outset starts from the publication S. M. van Netten "Laser interferometer microscope for the measurement of nanometer vibrational displacements of a light-scattering microscope object," J. Acoust. Soc. Am., 83 (4):1667-1074 (April 1988). In this measurement device, two laser beams are operated which interfere on the measurement object. Movements of the measurement object can only be measured perpendicular to the direction of observation (in-plane).